Host LL Cool J along with a star-studded presenter roster and performances from Taylor Swift, Elton John, The Black Keys, Frank Ocean and Fun. will provide the answers Sunday night.

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Hosts LL Cool J and Taylor Swift speak onstage at The Grammy Nominations Concert Live! held at Bridgestone Arena on December 5, 2012 in Nashville, Tennessee.

When host LL Cool J takes the stage at the 55th Annual Grammy Awards Sunday, he faces the almost herculean tasks of transitioning audience members — both in attendance at the Staples Center in Los Angeles and those viewing the broadcast at home — across acts of vastly different genres (pop, hard rock, spoken word, country, dance, alternative, R&B) and keeping the three-hour-plus show moving at a brisk pace.

Sounds about as easy as herding cats, no?

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Of all the questions generated in advance of the ceremony, the returning host's ability to emcee such an event is not one. LL Cool J ably took the reins in 2012 in the immediate wake of Whitney Houston's tragic death one day prior, maintaining a respectful tone while still embracing the anything-goes approach that makes the Grammys one of the more entertaining award shows.

It's anyone's guess, though, concerning the following:

2013 Grammy Nominations Concert

Who will be the big winner? After Adele's sweep last year, this year's list of winners is much harder to predict. Leading the field are Frank Ocean, Mumford & Sons, Fun., Kanye West, the Black Keys and Jay-Z, who received six nominations apiece.

The big categories? The title of Record of the Year is a battle between The Black Keys ("Lonely Boy"), Kelly Clarkson ("Stronger [What Doesn't Kill You]"), Fun. ("We Are Young"), Gotye ("Somebody That I Used to Know"), Frank Ocean ("Thinkin' About You") and Taylor Swift ("We Are Never Ever Getting Back Together").

Alabama Shakes, Fun., Hunter Hayes, the Lumineers and Frank Ocean are up for Best New Artist.

Song of the Year (awarded to the songwriter) will see "The A Team" (Ed Sheeran) up against "Call Me Maybe" (Tavish Crowe, Carly Rae Jepsen and Josh Ramsay), "Stronger (What Doesn't Kill You)" (Jörgen Elofsson, David Gamson, Greg Kurstin and Ali Tamposi), "Adorn" (Miguel Pimentel) and "We Are Young" (Jack Antonoff, Jeff Bhasker, Andrew Dost and Nate Ruess).

Will Rihanna attend on the arm of Chris Brown? Brown was sentenced to five years probation in 2009, when he was convicted of felony assault for attacking Rihanna after a pre-Grammy party. The pair are an item once more, with the "Diamonds" singer accompanying Brown to a probation hearing on Wednesday.

Will attendees respect the CBS dress code? Producers of the telecast reportedly sent out detailed guidelines to this year's nominees and attendees, advising them on the proper attire to wear to Sunday's show. According to the missive obtained by Deadline, attendees are requested to adhere to an apparent "network policy" on curbing those tendencies to dress like, well, someone going to the Grammys. Per the advisory: No butt cracks, thongs, underboobs, side boobs, sheer frocks, nipples or overly demonstrative groin areas. Overly demonstrative?

How will Taylor Swift open the show? Swift is no newbie when it comes to Grammy performances, but that doesn't mean she isn't feeling the pressure of taking on the number one slot. "Oh my god, it's Grammy week, it's so hectic. I have a lot to plan for with the opening performance and I'm just really hoping all the pieces come together this week. Because this is when it really gets really crazy, but it's all very exciting too," she told Ryan Seacrest during his radio show Thursday. On top of her nomination for record of the year, Swift received two nods for her "Hunger Games" soundtrack track "Safe & Sound."

What will Justin Timberlake do? Back in the musical spotlight (it's been four years since he performed at the ceremony), Timberlake's performance is set to surprise. Recording Academy President Neil Portnow told MTV that Timberlake fans are in for a "bit of a surprise. It will be worth watching, and with the Grammys, you always have the potential of seeing something first that you can't see anywhere else. And that's right in [Timberlake's] wheelhouse."

Who else will hit the stage? Other performances Sunday include one by Juanes. LL Cool J will join Travis Barker, Tom Morello, DJ Z-Trip and Public Enemy leader Chuck D in a hip-hop all-in. Chick Corea, Stanley Clarke and Kenny Garrett playing tribute to the late jazz great Dave Brubeck, who died in December. The Black Keys with Dr. John and the Preservation Hall Jazz Band will perform, too, and Elton John, Mumford & Sons, Mavis Staples, T Bone Burnett and Alabama Shakes' Brittany Howard and Zac Brown will perform a tribute to Levon Helm of the Band.